Prostaglandins play a major role in the inflammation process, and the inhibition of prostaglandin production, especially production of PGG.sub.2, PGH.sub.2 and PGE.sub.2, has been a common target of antiinflammatory drug discovery. However, common non-steroidal antiinflammatory drugs (NSAIDs) that are active in reducing the prostaglandin-induced pain and swelling associated with the inflammation process are also active in affecting other prostaglandin-regulated processes not associated with the inflammation process. Thus, use of high doses of most common NSAIDs can produce severe side effects, including life threatening ulcers, that limit their therapeutic potential. An alternative to NSAIDs is the use of corticosteroids, which have even more drastic side effects, especially when long term therapy is involved.
Previous NSAIDs have been found to prevent the production of prostaglandins by inhibiting enzymes in the human arachidonic acid/prostaglandin pathway including the enzyme cyclooxygenase (COX). The recent discovery of an inducible enzyme associated with inflammation (named "cyclooxygenase-2 (COX-2)" or "prostaglandin G/H synthase II") provides a viable target of inhibition which more effectively reduces inflammation and produces fewer and less drastic side effects.
In another portion of the arachidonic acid pathway, physiologically active leukotrienes, such as leukotriene B.sub.4 (LTB.sub.4), leukotriene C.sub.4 (LTC.sub.4) and leukotriene D.sub.4 (LTD.sub.4) and other metabolites, are produced by the 5-lipoxygenase-mediated (5-LO) oxidation of arachidonic acid. These leukotrienes have been implicated in various inflammation-related disorders and allergic diseases, and thus compounds which inhibit 5-lipoxygenase are useful in the treatment of disease states in which leukotrienes play an important role.
It is believed that selective dual inhibitors of both cyclooxygenase-2 and 5-lipoxygenase, which affect the two enzymes at low concentrations, will more completely and permanently affect the damage caused by the various diseases and disorders mediated by cyclooxygenase-2 and 5-lipoxygenase but without the gastrointestinal side effects associated with traditional NSAIDs.
The references below that disclose antiinflammatory activity, show continuing efforts to find a safe and effective antiinflammatory agent. The novel compounds disclosed herein are such safe and also effective antiinflammatory agents furthering such efforts. The invention's compounds are found to show usefulness in vivo as antiinflammatory agents with minimal side effects. The compounds disclosed herein preferably selectively inhibit cyclooxygenase-2 over cyclooxygenase-1.
Compounds which selectively inhibit cyclooxygenase-2 have been described in U.S. Pat. Nos. 5,380,738, 5,344,991, 5,393,790 and WO documents WO94/15932, WO94/27980, WO95/00501, WO94/13635, WO94/20480, and WO94/26731.
Compounds which inhibit 5-lipoxygenase have been described in U.S. Pat. Nos. 5,364,877, 5,302,603, 5,234,950, 5,098,932 and 5,354,865, among others.
Compounds which inhibit cyclooxygenase and 5-lipoxygenase have been described in U.S. Pat. Nos. 5,298,521, 5,242,940, 5,234,939, and 5,356,898, among others. However, these previous mixed inhibitors do not selectively inhibit cyclooxygenase-2 and therefore still cause the gastrointestinal side effects which substantially reduce their usage and effectiveness.
The invention's compounds are found to show usefulness in vivo as dual inhibitors of cyclooxygenase-2 and 5-lipoxygenase with minimal side effects.